Generally described, computing devices utilize a communication network, or a series of communication networks, to exchange data. In a common scenario, data to be exchanged is divided into a series of packets that can be transmitted between a sending computing device and a recipient computing device. In general, each packet can be considered to include two primary components, namely, control information and payload data. The control information corresponds to information utilized by one or more communication networks to deliver the payload data. For example, control information can include source and destination network addresses, error detection codes, packet sequencing identification, and the like. Typically, control information is found in packet headers and trailers included within the packet and adjacent to the payload data.
In practice, in a packet-switched communication network, packets are transmitted between multiple physical networks, or sub-networks. Generally, the physical networks include a number of hardware devices that receive packets from a source network component and forward the packet to a recipient network component. The packet routing hardware devices are typically referred to as routers. Generally described, routers can operate with two primary functions or planes. The first function corresponds to a control plane, in which the router learns the set of outgoing interfaces that are most appropriate for forwarding received packets to specific destinations. The second function is a forwarding plane, in which the router sends the received packet to an outbound interface.
To execute the forwarding plane functionality, routers can maintain a forwarding information base (“FIB”) that identifies, among other packet attribute information, destination information for at least a subset of possible network addresses, such as Internet Protocol (“IP”) addresses. In a typical embodiment, the FIB corresponds to a table of values specifying network forwarding information for the router. Meanwhile, to execute control plane functionality, routers can maintain a routing information base (“RIB”) that identifies routes through the network. The RIB can also contain metrics associated with those routes. As the router receives route updates, the router can update the RIB with announced or withdrawn routes. Generally, where the RIB identifies available routes, the FIB identifies an output interface corresponding to a selected route and the FIB is typically generated from information in the RIB.